When an ignition switch of a vehicle is on, a starting motor rotates and starts an engine in which a mixed gas of air and fuel may be combusted and explode in a combustion chamber of the engine. When an engine speed is equal to or more than a predetermined speed (for example, 800 RPM) after the engine starts, an engine control unit (ECU) controls the engine in an idle condition or an idle region. The ECU controls a fuel injection amount so that the engine speed may be a target speed in the idle region.
In the conventional engine control system and method, optimal values of engine control parameters (for example, an exhaust-gas recirculation (EGR) parameter, a boost parameter, an injection parameter, and so on) are logically inputted to control the engine in a room temperature condition, while engine developers analyze data with respect to an engine start test to search and apply optimal values in a low temperature condition of the engine.
Therefore, according to the conventional engine control system and method, since many tests are performed for each temperature and atmospheric pressure condition, development time and cost increase.
In addition, according to the conventional engine control system and method, when startability and idle stability deteriorate due to deterioration of hardware of the engine, a combustion state related to deterioration of the startability and idle stability may not be monitored.
Furthermore, according to the conventional engine control system and method, since a fuel injection amount is controlled to maintain engine idle speed in an idle region, indicated mean effective pressure (IMEP) control is difficult.
In the conventional engine control system and method, although a target control value for mass fraction burned 50% (MFB50), which is a point of time of 50% of the total amount of combustion heat is corrected considering influence by atmospheric temperature, atmospheric pressure, and coolant temperature, it is difficult to improve the idle stability due to the deterioration of the engine and an environmental condition in spite of performing MFB50 control with the corrected target control value.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.